McCartney and Wonder, who first collaborated on 1982's 'Ebony and Ivory', have come together again at Capitol Studios in Los Angeles for 'Only Our Hearts', one of McCartney's two original tracks featured on the album.

"Stevie came along to the studio in LA and he listened to the track for about ten minutes and he totally got it," McCartney said.

"He just went to the mic and within 20 minutes had nailed this dynamite solo. When you listen you just think, 'How do you come up with that?' But it's just because he is a genius, that's why."